Systemic sclerosis (SSc) is a devastating progressive multisystem fibrotic disease which affects the skin and other organs; there are currently no approved or effective therapies. The disease affects an estimated 300,000 Americans and is a major public health concern with high morbidity and mortality. The process of fibrosis is a common final pathway for multiple human diseases and diseases involving fibrosis cause nearly 45% of all deaths in industrialized nations. In this proposal, I plan to investigate the role of adipose PPAR-gamma on the process of fibrosis and specifically in animal models of SSc. Because we have observed that skin fibrosis is associated with subcutaneous adipose tissue loss and because work in our lab has demonstrated that PPAR-gamma is important in SSc pathogenesis, I hope to discover whether adipocytes play an important role in fibrosis and how PPAR-gamma may influence this. I first plan to investigate whether adipocyte PPAR-gamma gain of function can prevent fibrosis by applying the bleomycin-induced skin fibrosis model of SSc to transgenic mice with either constitutively activated PPAR-gamma or loss of PPAR-gamma repressors. I will then perform cell culture experiments to determine how PPAR-gamma function may alter adipocyte cell fate, production of soluble factors, and adipocyte effects on other important cells including fibroblasts and macrophages. This work will help determine the relevance of fat to the process of fibrosis and could potentially be paradigm shifting by implicating adipose tissue as an important contributor to fibrogenesis in SSc. The work in this training grant will be performed under the supervision of Dr. John Varga, one of the world's leading experts in SSc and the pathogenesis of fibrosis. In addition to having the mentorship of Dr Varga, because of the multidisciplinary nature of this project, I will have consultants with expertise in adipose biology and nuclear receptors (Dr Barish) as well as in mouse pathology (Dr. Tourtellotte). While SSc is a multiorgan disease, this work focuses on dermal fibrosis and therefore is highly relevant to the NIAMS mission of supporting research into the causes of musculoskeletal and skin disease and the training of scientists to perform such research. This mentored project consists both of formal didactics and research training and will lead me to develop expertise in PPAR-gamma biology and the relationship between adipogenesis and fibrosis. This work will help me to develop the knowledge and skills necessary to become an independent investigator and ultimately a future leader in rheumatology and the field of SSc research.